Crude oil is currently the source of most commodity and specialty organic chemicals. Many of these chemicals are employed in the manufacture of polymers and other materials. Examples include ethylene, propylene, styrene, bisphenol A, terephthalic acid, adipic acid, caprolactam, hexamethylene diamine, adiponitrile, caprolactone, acrylic acid, acrylonitrile, 1,6-hexanediol, 1,3-propanediol, and others. Crude oil is first refined into hydrocarbon intermediates such as ethylene, propylene, benzene, and cyclohexane. These hydrocarbon intermediates are then typically selectively oxidized using various processes to produce the desired chemical. For example, crude oil is refined into cyclohexane which is then selectively oxidized to “KA oil” which is then further oxidized for the production of adipic acid, an important industrial monomer used for the production of nylon 6,6. Many known processes are employed industrially to produce these petrochemicals from precursors found in crude oil. For example, see Ullmann's Encyclopedia of Industrial Chemistry, Wiley 2009 (7th edition), which is incorporated herein by reference.
For many years there has been interest in using biorenewable materials as a feedstock to replace or supplement crude oil. See, for example, Klass, Biomass for Renewable Energy, Fuels, and Chemicals, Academic Press, 1998, which is incorporated herein by reference. Moreover, there have been efforts to produce carboxylic acids from renewable resources using processes involving a combination of biocatalytic and chemocatalytic processes. See, for example, “Benzene-Free Synthesis of Adipic Acid”, Frost et al. Biotechnol. Prog. 2002, Vol. 18, pp. 201-211, and U.S. Pat. Nos. 4,400,468, and 5,487,987.
One of the major challenges for converting biorenewable resources such as carbohydrates (e.g., glucose derived from starch, cellulose or sucrose) to current commodity and specialty chemicals is the selective conversion of the primary alcohol (hydroxyl) group to a carboxyl group (COOH) in the presence of at least a secondary alcohol group.
Glucose can be obtained from various carbohydrate-containing sources including conventional biorenewable sources such as corn grain (maize), wheat, potato, cassava and rice as well as alternative sources such as energy crops, plant biomass, agricultural wastes, forestry residues, sugar processing residues and plant-derived household wastes. More generally, biorenewable sources include any renewable organic matter that includes a source of carbohydrates such as, for example, switch grass, miscanthus, trees (hardwood and softwood), vegetation, and crop residues (e.g., bagasse and corn stover). Other sources can include, for example, waste materials (e.g., spent paper, green waste, municipal waste, etc.).
Carbohydrates such as glucose may be isolated from biorenewable materials using methods that are known in the art. See, for example, Centi and van Santen, Catalysis for Renewables, Wiley-VCH, Weinheim 2007; Kamm, Gruber and Kamm, Biorefineries-Industrial Processes and Products, Wiley-VCH, Weinheim 2006; Shang-Tian Yang, Bioprocessing for Value-Added Products from Renewable Resources New Technologies and Applications, Elsevier B. V. 2007; Furia, Starch in the Food Industry, Chapter 8, CRC Handbook of Food Additives 2nd Edition CRC Press, 1973. See also chapters devoted to Starch, Sugar and Syrups within Kirk-Othmer Encyclopedia of Chemical Technology 5th Edition, John Wiley and Sons 2001. Also, processes to convert starch to glucose are known in the art, see, for example, Schenck, “Glucose and Glucose-containing Syrups” in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH 2009. Furthermore, methods to convert cellulose to glucose are known in the art, see, for example, Centi and van Santen, Catalysis for Renewables, Wiley-VCH, Weinheim 2007; Kamm, Gruber and Kamm, Biorefineries-Industrial Processes and Products, Wiley-VCH, Weinheim 2006; Shang-Tian Yang, Bioprocessing for Value-Added Products from Renewable Resources New Technologies and Applications, Elsevier B. V. 2007.
The selective oxidation of glucose to glucaric acid has been attempted by using oxidation methods that employ platinum catalysts. See, for example, U.S. Pat. No. 2,472,168, which illustrates a method for the preparation of glucaric acid from glucose using a platinum catalyst in the presence of oxygen and a base. Further examples of the preparation of glucaric acid from glucose using a platinum catalyst in the presence of oxygen and a base are illustrated in the Journal of Catalysis Vol. 67, p. 1-13, and p. 14-20 (1981). Other oxidation methods have also been employed; see, for example, U.S. Pat. Nos. 6,049,004, 5,599,977, and 6,498,269, WO 2008/021054 and J. Chem. Technol. Biotechnol. Vol. 76, p. 186-190 (2001); J. Agr. Food Chem. Vol. 1, p. 779-783 (1953); J. Carbohydrate Chem. Vol. 21, p. 65-77 (2002); Carbohydrate Res. Vol. 337, p. 1059-1063 (2002); Carbohydrate Res. 336, p. 75-78 (2001); and Carbohydrate Res. Vol. 330, p. 21-29 (2001). However, these processes suffer from economic shortcomings resulting from, among other matters, process yield limitations, low conversion rates, and limited selectivity due to shortcomings in the performance of existing catalysts. None of these catalysts or the processes employing them are used industrially for the selective oxidation of glucose-containing carbohydrates to manufacture specialty or industrial carboxylic acids or derivatives thereof.
Thus, there remains a need for new, industrially scalable catalysts for the selective and commercially-meaningful conversion of a primary hydroxyl group to a carboxyl group of compositions comprising a primary hydroxyl group and at least a secondary hydroxyl group. Desirably, there is the need to convert biorenewable materials such as, for example, carbohydrates or polyols, to specialty or industrial carboxylic acids and derivatives thereof, and more particularly, e.g., to convert glucose (derived from starch, cellulose or sucrose) to important chemicals such as glucaric acid and derivatives thereof.